Early predicting the efficacy of bevacizumab combined with conventional therapy in newly diagnosed glioblastoma could help us to identify the suitable patients to receive suitable treatment in GBM. Thus, characterizing the blood flow and blood volume in the tumor and their changes during therapy might provide information on vasculature growth or collapse,edema formation, tumor growth, and/or cell death(necrosis) .We decided to investigate whether the estimation of blood circulation in tumor, using MRI,PET could be used as a surrogate marker to predict the early response of GBM to bevacizumab.